This invention generally relates to the field of intravascular catheters which are advanceable over a guidewire into a desired region of a patient's vasculature, and particularly to an intravascular catheter which is advanceable into a patient's coronary arteries for therapeutic or diagnostic procedures therein.
In percutaneous transluminal coronary angioplasty (PCTA) procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced by a Seldinger techniques into the cardiovascular system of a patient and advanced within the system until the preshaped distal tip of the guiding catheter is disposed within the ascending aorta adjacent the ostium of the desired coronary artery. The guiding catheter is relatively stiff and when it is twisted or torqued from its proximal end, which extends outside the patient, the distal tip of the guiding catheter may be guided into the desired coronary ostium. With the distal end of the guiding catheter well seated within the ostium of the desired coronary artery, a balloon dilatation catheter is introduced into and advanced through the guiding catheter and out the distal tip thereof into the patient's coronary artery until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion to be dilated. Once properly positioned, the balloon is inflated one or more times to a predetermined size with radiopague liquid at relatively high pressures (e.g., generally 4-12 atmospheres) to dilate the stenotic region of the diseased artery. When the dilatations have been completed, the balloon is finally deflated so that the dilatation catheter can be removed from the dilated stenosis to allow the resumption of increased blood flow through the dilated artery.
One frequently used type of angioplasty catheter is an over-the-wire type catheter which has an inner lumen extending within the catheter shaft which is configured to slidably receive a guidewire which facilitates advancement of the catheter over the guidewire to the desired location within the patient's coronary arteries. The guidewire receiving inner lumen may extend the entire length of the catheter as in conventional over-the-wire catheters or only in the distal portion of the catheter between a distal guidewire port and a proximal guidewire port which is spaced a short distance proximally from the distal guidewire port and a substantial distance from the proximal end of the catheter as in rapid exchange type catheters.
It is not uncommon during an angioplasty procedure to exchange the dilatation catheter once the dilatation catheter has been advanced within the patient's arterial system. For example, if the physician determines that the inflated size of the balloon or the length of the balloon is inappropriate for the stenosis to be dilated, the dilatation catheter will be withdrawn and another, more appropriately sized dilatation catheter will be advanced into the coronary artery over the guidewire which remains in-place to dilate the stenosis. However, if the catheter is a conventional over-the-wire catheter, before the catheter is withdrawn either the guidewire in place must be replaced with an exchange wire, which is similar to the in-place guidewire except about twice as long, e.g. about 300 cm, as the normal guidewire or an extension wire about the same length as the in-place guidewire must be secured to the proximal end of the in-place guidewire to facilitate the withdrawal of the catheter from the patient's vasculature without loss of the distal position of the guidewire. The reason that it is important to maintain the position of the distal tip of the guidewire across the stenosis, is that, if the guidewire is withdrawn, it may take the attending physician a substantial amount of time, e.g. from about 15 minutes up to about two hours or more, to advance a replacement guidewire into the patient's coronary artery and across the stenosis to be dilated and to then advance the dilatation catheter until the dilatation balloon thereof crosses the stenotic region. The original unsuitable catheter is usually discarded.
In some instances, after a dilatation is complete, it is necessary or at least desireable to implant a stent in the dilated stenotic region to provide long term patency thereto. In these cases the dilatation catheter which has performed the dilatation is removed and another balloon catheter having an unexpanded stent mounted about the balloon is advanced over the in-place guidewire to the stenotic region where the balloon is inflated to expand and thus implant the stent in the stenotic region. In this case the original angioplasty catheter is also discarded.
What has been needed and heretofore unavailable is a system for easily changing a shaft section of an intravascular catheter without the need to discard the entire catheter. The present invention satisfies these and other needs.